There is definitely a shortage of mental health professionals, and an increase in people seeking help. I often refer people to psychologytoday.com. You can search by location, insurance, age, issues to address, etc. Listings are usually pretty up to date when it comes to whether or not they are taking new clients.
You can also ask through the school if there is anyone she can see in the meantime- is there a school psychologist or social worker?
While waiting to get in to talk to someone (and I do think that therapy is a good idea), would she be amenable to trying some basic mindfulness exercises? 5 Things is a simple way to center and ground and get your mind into the present.
ETA: Even though it's a children's book, I highly, highly recommend I Am Peace by Susan Verde (I think.) I give it as gifts to my interns before their certification exam and I use it often with my clients of all ages struggling with anxiety (grief counselor, but anxiety often skyrockets in grief, so I do a lot of teaching of coping mechanisms.)
